i::=:::
0+::=1r
1+::=+0
(+::=(1r
r0::=0r
r1::=1r
r|0::=+|
r|)::=s|)
0s::=s0
1s::=s1
(s1::=(Xt
t000::=~>
t001::=~<
t010::=~+
t011::=~-
t100::=~.
t101::=~,
t110::=~[
t111::=~]
(X1::=(Xt1
(X0::=(Xt0
::=
(0r|i)
